Peter Crisp wrote:The problem is if the next gen isn't going to get released until Christmas 2020 will they have enough decent gameplay to show from those new machines?

No, and that was the problem at E3 2012. PS4 and XBO were a year away from being unveiled but no one could announce new games for the secret consoles so we saw VERY few new games at the show. Last of Us and Halo 4 gameplay were the only big things I remember.

Most big developers (Guerilla, Sony Santa Monica) who've released non-annualised games in the last 2 years will now be well into their 3-4 year development cycles on next-gen titles, but won't be able to announce the games until the consoles are announced.

Next year's E3 will be a quiet one focusing on games that are announced this year. There might be some cross-gen titles announced, but not much.